package SQLite3;

/**
 * Callback interface for SQLite's user defined functions. Each callback method
 * receives a <A HREF="FunctionContext.html">FunctionContext</A> object which is
 * used to set the function result or error code. <BR>
 * <BR>
 * Example:<BR>
 * 
 * <PRE>
 *   class SinFunc implements SQLite.Function {
 *     public void function(SQLite.FunctionContext fc, String args[]) {
 *       try {
 *         Double d = new Double(args[0]);
 *         fc.set_result(Math.sin(d.doubleValue()));
 *       } catch (Exception e) {
 *         fc.set_error("sin(" + args[0] + "):" + e);
 *       }
 *     }
 *     ...
 *   }
 *   SQLite.Database db = new SQLite.Database();
 *   db.open("db", 0);
 *   db.create_function("sin", 1, SinFunc);
 *   ...
 *   db.exec("select sin(1.0) from test", null);
 * </PRE>
 */

public interface Function {

	/**
	 * Callback for regular function.
	 * 
	 * @param fc
	 *            function's context for reporting result
	 * @param args
	 *            String array of arguments
	 */

	public void function(FunctionContext fc, String args[]);

	/**
	 * Callback for one step in aggregate function.
	 * 
	 * @param fc
	 *            function's context for reporting result
	 * @param args
	 *            String array of arguments
	 */

	public void step(FunctionContext fc, String args[]);

	/**
	 * Callback for final step in aggregate function.
	 * 
	 * @param fc
	 *            function's context for reporting result
	 */

	public void last_step(FunctionContext fc);

}
